1. Field of the Invention
The present invention relates to a grounding structure and method for a metal cooling module which cools heat-generating components mounted on a printed circuit board in an electronic apparatus, and an electronic apparatus provided with the grounding structure.
2. Description of the Related Art
An electronic apparatus, such as a personal computer, incorporates a number of electronic components that consume a great amount of power and generate heat while operating, such as a CPU, peripheral controllers and a display controller, and the like, the components being formed of integrated circuits (IC). Therefore, such an electronic apparatus is equipped with a cooling module for dissipating heat generated by the electronic components. As a cooling module, a metal module made of, for example, aluminum is generally used in view of its high cooling efficiency and low cost.
Further, in an electronic apparatus that employs a mounting method such as the BGA (Ball Grid Array), a recent mainstream mounting method, the range of pressure that can be applied to the device is predetermined. Accordingly, when arranging a cooling module for heat radiation in contact with, for example, a CPU, it is difficult to adjust the pressure simply by screwing the module into the printed circuit board with the CPU interposed between the board and the module. Because of this, in general, a spring, for example, is additionally used to adjust the pressure vertically applied to the CPU by the cooling module.
Furthermore, it is necessary to secure the cooling module to the printed circuit board with a pressure falling within a predetermined range applied to the board. If the pressure is low, the cooling module may vibrate due to the magnetic field created by the current that flows when the CPU is operating. As a result, the cooling module cannot be grounded securely, which makes it electrically unstable.
Also, in accordance with increases in the operating speeds of electronic components such as CPUs, the power consumption of such electronic components has increased markedly. Accordingly, the cooling module corresponding to each electronic component has been enlarged. Under these circumstances, when a CPU is operating, considerable vibration occurs, particularly, at an end portion of the cooling module. Moreover, electromagnetic radiation from the CPU is picked up by the cooling module, with the result that extra noise is generated by the cooling module, adversely affecting peripheral electronic apparatuses.
To avoid the above problems, for example, conductive elastic members such as gaskets are held between opposite ends of the cooling module and printed circuit board, and are connected to ground planes on the board, thereby providing secondary suppression of vertical vibration of the cooling module while grounding the module.
However, it is necessary to prevent the secondary-fixing/grounding means from increasing the pressure applied to the CPU. Because of this, the secondary-fixing/grounding means cannot be brought into contact with the cooling module with a sufficient force, and therefore radiated noise cannot be adequately suppressed.
The present invention has been developed under the above-described circumstances, and its object is to provide a cooling module grounding structure and method and an electronic apparatus with the grounding structure, which can maintain a cooling module at ground potential in a stable manner, and reduce the amount of noise generated by an electronic component during its operation.
To satisfy the object, according to an aspect of the invention, there is provided a grounding structure for a cooling module, comprising: a printed circuit board installed in an electronic apparatus; an electronic component mounted on the printed circuit board; a metal cooling module opposed to the electronic component to cool the electronic component; a vertical support mechanism which supports the cooling module such that the cooling module is kept in pressure contact with the electronic component, the pressure being exerted perpendicular to the surface of the printed circuit board and falling within a predetermined range; and a ground portion electrically grounding the cooling module.
According to another aspect of the invention, there is provided an electronic apparatus comprising: an apparatus body; a printed circuit board installed in the apparatus body and provided with an electronic component; a metal cooling module installed in the apparatus body and opposed to the electronic component, the metal cooling module being configured to cool the electronic component; a vertical support mechanism which supports the cooling module such that the cooling module is kept in pressure contact with the electronic component, the pressure being exerted perpendicular to the surface of the printed circuit board and falling within a predetermined range; and a ground portion electrically connected to the cooling module to ground it.
According to yet another aspect of the invention, there is provided a method of grounding a cooling module, comprising: mounting an electronic component on a printed circuit board; securing a metal cooling module, configured to cool the electronic component, to the printed circuit board by a force exerted perpendicular to the printed circuit board such that the cooling module is kept in pressure contact with the electronic component, the pressure falling within a predetermined range; and pressing and fixing the cooling module by a force exerted parallel to the printed circuit board, thereby connecting the cooling module to a ground area on the printed circuit board to ground the cooling module.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.